X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=compiler%2Ftypecheck%2FTcType.lhs;h=625f855f4cba0c61481aeb2a562b721c345b08a0;hb=06f6f35dadc461336675e6d2b8a2192b1f518a1b;hp=388a28d08040f22d173d8a9ba6836a28fe8c018c;hpb=7fc749a43b4b6b85d234fa95d4928648259584f4;p=ghc-hetmet.git

diff --git a/compiler/typecheck/TcType.lhs b/compiler/typecheck/TcType.lhs
index 388a28d..625f855 100644
--- a/compiler/typecheck/TcType.lhs
+++ b/compiler/typecheck/TcType.lhs
@@ -38,7 +38,7 @@ module TcType (
   isImmutableTyVar, isSkolemTyVar, isMetaTyVar, isBoxyTyVar, 
   isSigTyVar, isExistentialTyVar,  isTyConableTyVar,
   metaTvRef, 
-  isFlexi, isIndirect, 
+  isFlexi, isIndirect, isRuntimeUnk, isUnk,
 
   --------------------------------
   -- Builders
@@ -457,7 +457,7 @@ pprSkolTvBinding tv
     ppr_details (MetaTv (SigTv info) _) = ppr_skol info
     ppr_details (SkolemTv info)		= ppr_skol info
 
-    ppr_skol UnkSkol	    = empty	-- Unhelpful; omit
+    ppr_skol UnkSkol	    = ptext SLIT("is an unknown type variable")	-- Unhelpful
     ppr_skol RuntimeUnkSkol = ptext SLIT("is an unknown runtime type")
     ppr_skol info           = sep [ptext SLIT("is a rigid type variable bound by"),
 				   sep [pprSkolInfo info, 
@@ -556,6 +556,16 @@ isFlexi other     = False
 
 isIndirect (Indirect _) = True
 isIndirect other        = False
+
+isRuntimeUnk :: TyVar -> Bool
+isRuntimeUnk x | isTcTyVar x
+               , SkolemTv RuntimeUnkSkol <- tcTyVarDetails x = True
+               | otherwise = False
+
+isUnk :: TyVar -> Bool
+isUnk x | isTcTyVar x
+        , SkolemTv UnkSkol <- tcTyVarDetails x = True
+        | otherwise = False
 \end{code}
 
 
@@ -1052,6 +1062,15 @@ exactTyVarsOfType is used by the type checker to figure out exactly
 which type variables are mentioned in a type.  It's also used in the
 smart-app checking code --- see TcExpr.tcIdApp
 
+On the other hand, consider a *top-level* definition
+	f = (\x -> x) :: T a -> T a
+If we don't abstract over 'a' it'll get fixed to GHC.Prim.Any, and then
+if we have an application like (f "x") we get a confusing error message 
+involving Any.  So the conclusion is this: when generalising
+  - at top level use tyVarsOfType
+  - in nested bindings use exactTyVarsOfType
+See Trac #1813 for example.
+
 \begin{code}
 exactTyVarsOfType :: TcType -> TyVarSet
 -- Find the free type variables (of any kind)
@@ -1276,6 +1295,7 @@ legalFFITyCon tc
 marshalableTyCon dflags tc
   =  (dopt Opt_UnliftedFFITypes dflags 
       && isUnLiftedTyCon tc
+      && not (isUnboxedTupleTyCon tc)
       && case tyConPrimRep tc of	-- Note [Marshalling VoidRep]
 	   VoidRep -> False
 	   other   -> True)